Process for reforming porphyrin metallo complexes from heavy oils



United States atent O PROCESS FOR REFORMING PORPHYRIN NIIELEALLO COlVIPLEXES FROM HEAVY John G. Erdman, Allison Park, and Bernard J. Lerner, OHara Township, Allegheny County, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware N 0 Drawing. Application April 17, 1957 Serial No. 653,275

17 Claims. (Cl. 208-253) This invention relates to a process for the destruction of porphyrin metallo complexes and more particularly to a process for effectively reducing the porphyrin metallo complex content in mineral oils and other bitumens.

A recent problem of considerable importance to the petroleum industry is the presence of heavy metals such as vanadium, nickel, iron and copper in certain petroleum crude oils, residual oils and distillate fractions derived from such crudes. The presence of such metals in catalytic cracking charge stocks is undesirable in that the metals cause inactivation and/or decrease the selectivity of the cracking catalyst. Furthermore, these metals particularly vanadium, are undesirable in residual petroleum fractions used as fuel because of the corrosion and pitting of metals of construction resulting from contact with the hot ash obtained upon combustion of such residual fuels.

With the increasing use of crude oils obtained from foreign sources such as the Middle East and South America, the problem has achieved considerable magnitude. The reason for this is the presence of relatively large amounts of the heavy metals in such crudes. The amounts of such metals in domestic sources of crude oil such as Mid-Continent and East Texas crudes, are so small as to present no problem in the refining of the crudes and in the use of the petroleum fractions obtained from such crudes. For example, with two Texas crudes containing only 0.1 part per million of vanadium and two and four parts per million of nickel, these crudes can be processed and their fractions employed in the usual way without encountering any serious problems due to metals content. On the other hand with a Kuwait crude containing 29 parts per million of vanadium and 8.5 parts per million of nickel, the problem does exist, while with such Venezuelan crudes which contain 200 to 400 parts per million or more of vanadium and 16.7 to 59 parts per million or more of nickel, the problem is serious. Briefly stated, the oils with which this invention is concerned are those which contain suflicient amounts of heavy metals so as to cause catalyst contamination problems in refining processes and/or corrosion problems in the use as fuel of the residual fractions.

The conventional methods commonly employed for treating petroleum are not efiective for the removal of metals complexed to porphyrin aggregates. A consideration of the properties of these metallo porphyrin complexes provides an explanation for the extreme difiiculty experienced in removing them. It can be demonstrated that vanadium and similar heavy metal complexes of alkyl substituted porphyrins, are neutral, oil-soluble and less strongly adsorbed on polar surfaces than the higher molecular weight aromatic hydrocarbons and the nonhydrocarbon substituents of crude oil or petroleum distillates. For these reasons, conventional treatments such as acid treating, clay treating and the like, are not practical for the removal of the complexes.

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The porphyrin metallo complexes are thermally stable up to and beyond temperatures of 660 F. and at elevated temperatures they sublime without decomposition. Furthermore, it has been determined that the porphyrin metallo complexes possess sufficient volatility so that at high temperatures they distill and pass into the distillates. Accordingly, their removal by thermal treatment alone is not feasible.

We have now found that porphyrin metallo complexes present in mineral oils can be destroyed by contacting them for a sufficient time with a treating agent selected from among the alkali metals, alkaline earth metals, aluminum and the hydrides thereof.

Specific agents which have been found suitable for use to destroy the porphyrin metallo complexes are: the alkali metals, for example, sodium, potassium, lithium; the alkaline earth metals, magnesium, calcium, strontium and barium; aluminum; and the respective hydrides of these metals. Of these agents, sodium and sodium hydride are preferred because of their availability and lower cost.

In accordance with our invention, a mineral oil containing relatively high amounts of heavy metals in the form of porphyrin metallo complexes is contacted at an elevated temperature with the above mentioned treating agents for a period of time to effectively destroy the organic complexes. The porphyrin metallo complexes can be destroyed in this manner when present in crude oils or distillate fractions thereof, such as fuel oils and catalytic cracking charge stocks, without affecting the i hydrocarbon portion of the oil adversely.

After the porphyrin metallo complexes have been contacted with the treating agents of the invention for a sufficient time, the complexes are thereby substantially destroyed and the heavy metal substituents of the complexes can be readily separated from the oil. For example, the metals after treatment may be separated from the oil by extraction, adsorption, filtration, centrifiugation, ion exchange and the like. An alternate separation procedure which may be employed is to simply distill the volatile hydrocarbons away from the metals which by the process of the invention have been rendered non-volatile to produce substantially metals free distillates.

To achieve maximum efiiciency in the destruction of the organic complexes present in the mineral oil, the treating agents should be intimately admixed with the oil. Accordingly, it is desirable to employ the treating agents in the form of finely divided particles.

The treating operation may be effected in general at temperatures of between about 200 F. and 660 F., although somewhat higher or lower temperatures can be used. Temperatures in the upper portion of the range mentioned are preferred to effect a more rapid destruction of the porphyrin metallo complexes.

The time of treatment or contact time depends upon the amount of the porphyrin metallo complexes present in the mineral oil and the temperature at which the treating operation is conducted. However, to reduce the porphyrin metallo complex content sufliciently so as to avoid the deleterious eifeots of the heavy metals, the oil must be contacted with the treating agents for a period of time sufiicient to cause cleavage of the organic complexes. Thus, we have found that when treating at a temperature of about 480 F. mineral oils containing relatively small amounts of heavy metals, as for example, 22 parts per million vanadium, a contact time of about one hour is ordinarily required to sufliciently reduce the metals content. With increasing metals content, the con tact time required to achieve a satisfactory reduction of metals content is increased and may be as high as nine hours or more. We have found further, that the contact time can be materially shortened by etfecting the contact of the mineral oil with the treating agents in the presence of an oxygen-containing gas such as air or oxygen itself. When employing this preferred modification of the invention, contact times as low as 15 minutes can be utilized to give a satisfactory reduction in metals content.

The amount of oxygen containing gas present during the treating operation does not appear to be critical and the efliciency of the process is improved as long as there is some free or uncombined oxygen in contact with the oil undergoing treatment.

The amounts of the treating agent employed depend on the amount of metallo porphyrins present in the oil. It is preferred to employ the treating agents in an amount equivalent to 0.02 to 2 weight percent of the oil. When employed in amounts within this range, the treating agents are ordinarily present in a ratio of at least 25 parts treating agent per part of heavy metal and are effective to destroy substantially all of the metallo porphyrins and to render the metal substituents of the complexes readily removable from the oil.

The pressure at which the treating operation is effected is not critical and either a vapor phase operation or a liquid phase operation may be employed. Furthermore, the treating operation can be employed as a separate operation or it may be carried out simultaneously with other refining operations.

The following examples illustrate the effectiveness of the treating agents of this invention in destroying the porphyrin metallo complexes in mineral oils.

Example I In a round bottom, three-necked flask, equipped with stirrer, thermometer, and nitrogen inlet tube, was placed 258.7 grams of a Mara catalytic cracking charge stock having a boiling range at atmospheric pressure of 600- 1135 F. To this oil was then added 14.7 g. of a sodium emulsion in a white mineral oil containing approximately 21.2% by weight of metallic sodium, thus making the concentration of sodium in the reaction mixture approximately 1%. The mixture was heated with stirring to 480 F. in an atmosphere of nitrogen and maintained at this temperature for twelve hours. At intervals, aliquots of the oil were withdrawn for determination of the concentration of porphyrin metallo complexes remaining. For this purpose the aliquots were treated as follows:

The following results were obtained:

Cone. (p.p.m.) Cone. Reaction Time (hours) of Vanadium- (p.p.n1 t Porphyrin Vanadlum Complex Example I! The procedure of Example I was repeated using 451 grams of the same Mara catalytic cracking charge stock and 16.1 grams of a sodium hydride emulsion in white mineral oil containing approximately 21.2% by weight of sodium hydride. Thus, the concentration of sodium hydride in the reaction mixture was approximately 1%.

The procedure of Example I was repeated using a raw Mara crude oil which had been topped to approximately 500 F. To 332 grams of the topped Mara crude was added 17.9 grams of a sodium emulsion in white mineral oil (containing 21.2% by weight of metallic sodium) giving a resultant sodium concentration in the reaction mixture of approximately 1%. The results obtained were as follows:

Cone. (p.p.m.) of Vanadium Gone. (p.p.m.) of Vanadium- Porphyrin Complex Reaction Time (hours) Example IV The procedure of Example I was repeated using 300 grams of a substantially metals free catalytic cracking charge stock having a boiling range at atmospheric pressure of 752-1135 F. to which had been added 60 mg. etioporphyrin I nickel complex. To this oil was then added 9 grams of a sodium hydride emulsion in white mineral oil containing approximately 27.2% by Weight of sodium hydride, thus making the concentration of sodium hydride in the reaction mixture approximately 0.8%. The followmg results were obtamed:

Gone. (p.p.m.) 01 Reaction Time (hours) Nickel- Porphyrin Complex Example V In a 500 milliliter three-necked round bottom glass flask equipped with a stirrer and dip tube for gas injection was placed 132.1 grams of a solution of pure synthetic etioporphyrin I vanadium complex in white mineral oil. The solution was heated to approximately 392 F. in an atmosphere of nitrogen. After the desired temperature was reached 0.0338 gram of sodium was added to the oil solution to give a sodium concentration of approximately 0.025%. Air was then bubbled through the stirred solution and 10 milliliter samplesvwere Withdrawn every minutes for spectral analysis. results were obtained:

The following Oonc. (p.p.m.) of

Vanadium- Porphyrin Complex Reaction Time (hours) Example VI Cone. (p.p.m.) of

Vanadium- Porphyrin Complex Reaction Time (hours) Example VII A solution of synthetic etioporphyrin I vanadium complex was prepared in white mineral oil and treated at approximately 480 F. in an atmosphere of nitrogen with a suspension of finely divided calcium hydride in White mineral oil. The calcium hydride represented approximately 1% by weight of the reaction mixture.

Spectral analysis gave the following results:

Oonc. (p.p.m.) of

Vanadium- Porphyrin Complex Reaction Time (hours) Example VIII In a 500 ml., three-necked round bottom flask, equipped with stirrer and dip tube for gas injection, was placed 128.1 grams of a Mara catalytic cracking charge stock having a boiling range at atmospheric pressure of 600-1050 F. The oil was heated to 392 F. in an atmosphere of nitrogen. After the desired temperature was reached 0.0376 gram of sodium was added to the oil solution to give a sodium concentration of approximately 0.029% Air was then bubbled through the oil for two hours. The following results were obtained by spectral analysis.

Cone. (p.p.m.) of

Vanadium- Porphyrin Complex Reaction Time (hours) The foregoing examples demonstrate clearly the significant reduction in porphydrin metallo complex content of mineral oils obtained by treatment in accordance with the invention. Examples V, VI and VIII illustrate particularly the increased efficiency achieved by eifecting the contact of the porphyrin metallo complex with the treating agents of the invention in the presence of air. As shown in these examples, in the presence of air, the contact time required to destroy the porphyrin metallo complexes is considerably shortened.

As mentioned heretofore many suitable methods are available for separating the heavy metals from the petroleum stock after treatment in accordance with the invention. The following examples illustrate the ease with which the heavy metals may be separated from a mineral oil after the porphyrin metallo complexes have been destroyed.

Example IX Sample Total Vanadi- Total Nickel,

um, p.p.1;n. p.p.m.

Reaction Mixture before washing. 31. 6 30. 7 1. 92 1. 93 Reaction Mixture after washing 8. 50 8. 57 1. 13 1.25

Example X ml. of a solution of synthetic etioporphyrin I vanadium complex in mineral oil was treated with metallic sodium in a concentration of approximately 0.047% by weight at 392 F. Air was blown through the stirred solution for two hours. The solution was then divided into two portions and one portion was filtered. Both the filtered and unfiltered portions of the treated oil were then analyzed for total vanadium by sulfate ashing and spectrographic analysis. The unfiltered oil solution was found to contain 13.2 ppm. vanadium. The filtered oil solution was found to contain 2.6 ppm. of vanadium.

As seen from Examples IX and X, after treatment in accordance with the invention the metal substituents of the porphynin metallo complexes: present in mineral oils can be readily separated from the oils.

From the foregoing description of the invention it is apparent that the invention provides a particularly effective method for destroying ponphyrin metallo complexes in mineral oils and rendering the heavy metal components of the organic complexes readily removable from the oil. A major advantage of the invention is the fact that it can be utilized to beneficiate a variety of petroleum feed stocks without causing the hydrocarbon portion of the feed stock to be aifected deleteriou-sly. After separation from the oil, the heavy metals can be easily recovered, making the invention particularly advantageous economically for treating crude oils having high metals content.

Resort may be had to the various modifications and variations which fall within the spirit of the invention and the scope of the appended claims.

We claim:

1. A process for the destruction of porphyrin metallo complexes which comprises contacting said complexes, for a time and in an amount sufficient to cause cleavage of said complexes, with a treating agent selected from the group consisting of the alkali metals, the alkaline earth metals, aluminum and the hydrides thereof.

2; The process of claim 1 wherein the metal of the. said porphyrin metallo complex is vanadium.

3. The process of claim 1 wherein the metal of the said porphyrin metallo complex is nickel.

4; The process of claim 1 wherein the porphyrin metallo complexes are present ina mineral oil.

5. The process of claim 1 wherein the porphyrin metallo complexes are present in a crude oil.

6. The process of claim 1 wherein the mineral oil is a petroleum fraction. I

7. A process for removing heavy metals from a mineral oil containing said heavy metals in the form of porphyrin metallo complexes which comprises contacting the oil for a time suflicient to cause cleavage of the porphyrin metallo complexes present therein, with a treating agent selected from the group consisting of the ,alkali metals, the alkaline earth metals, aluminum and the hydrides thereof, then separating the heavy metals from the oil.

8. The process of claim 7, wherein the said treating agent is metallic sodium.

9. The process of claim 7, wherein the said treating agent is employed in an amount from about 0.02% to 2% by weight of oil.

10. The process of claim 7, wherein the heavy metals are separated from the oil by Washing.

11. The process of claim 7, wherein the heavy metals are separated from the oil by filtration.

12. A process for reducing the porphyrin metallo complex content of a catalytic cracking charge stock which comprises contacting a crude oil containing porphyrin metallo complexes, for a time sufficient to cause cleavage of the said porphyrin metallo complexes present therein, with a treating agentselected from the group consisting of the alkali metals, the alkaline earth metals, aluminum and the hydrides thereof and distilling the treated crude oil to obtain a catalytic charge stock of reduced porphyrin metallo complex content.

13. The process of claim 12 wherein the said treating agent is employed in an amount from about 0.02% to 2% by weight of oil.

14.- A process for removing heavy metals from a minagent selected from the group consisting of the alkali metals, the alkaline earth metals, aluminum and the hydrides thereof, said contact between the oil and treating agent being eflfected in the presence of an oxygen containing gas and then separating the said metals fronr the oil.

15. The process of claim 14 wherein the said treating agent is employed in an amount from about 0.02% to 2% by weight of oil.

16. A process for reducing the porphyrin metallo complex content of a catalytic cracking charge stock which comprises contacting a crude oil containing porphyrin metallo complexes, for a time suflicient to cause cleavage of the porphyrin metallo complexes present therein, with a treating agent selected from the group consisting of the alkali metals, the alkaline earth metals, aluminum and-the hydrides thereof, said contact between the oil andtreating agent being elfected in the presence of an oxygen containing gas, then distilling the treated crude oil to obtain a catalytic charge stock of reduced porphyrin metallo complex content.

17. A process for removing heavy metals from a mineral oil containing said heavy metals in the form of porphyrin metallo complexes which comprises contacting the oil with metallic sodium for atime sufficient to cause cleavage of the porphyrin metallo complexes present therein, said contact between the oil and metallic sodium being elfected in the presence of an oxygen containing gas andthen' separating said metals fromthe- 

1. A PROCESS FOR THE DESTRUCTION OF PORPHYRIN METALLO COMPLEXES WHICH COMPRISES CONTACTING SAID COMPLEXES, FOR A TIME AND IN AN AMOUNT SUFFICIENT TO CAUSE CLEAVAGE OF SAID COMPLEXES, WITH A TREATING AGENT SELECTED FROM THE GROUP CONSISTING OF THE ALKALI METALS, THE ALKALINE EARTH METALS, ALUMINUM AND THE HYDIDES THEREOF. 